Alright, so, I was messing around with Diddy in training mode, and, if you were to run off the edge, your momentum from dashing would still be evident for a few frames, SO, if you were to use an animation to HOLD that momentum, such as a banana pull, you'll carry the momentum from your dash. The earlier you do it when you come off the edge, the faster and farther you'll go. Try doing this with GW and never release your Down B, you'll carry your momentum until you release Down B. For some reason, this doesn't work (or is just REALLY hard to do) for all characters. It can be used with other B attacks, depending on their physics, such as Judge Hammer.
INPUT? >:O
INPUT? >:O